Controlling a robot by determining the distance of a state variable of the robot from a limit, and triggering a safety action when this distance satisfies a prespecified condition, is well-known from practical in-house experience. A STOP 0, for example, can be triggered, i.e. the robot can be shut down by interrupting the power supply, as soon as its Tool Center Point (TCP) exceeds a work space limit or its speed exceeds a permissible speed limit.
It is also well-known from practical in-house experience, that this can be tested by manually taking the robot to such limits; i.e. manually taking the TCP over the work space limit, or operating with a speed exceeding the speed limit, to test if this triggers the safety action.
Particularly for more complex limits, such as work space limits that are defined by curved hypersurfaces in the state space of the robot and/or as a function of the state variable itself, however, this type of test is difficult and is notably not very intuitive.
Besides determining a distance to a prespecified limit, identifying the distances of a current position to a group of saved positions and selecting that saved position, of which the distance to the current position is minimal in a program, is also well-known from our own DE 10 2008 062 623 A1.